Telling Untruths

If it turns out that John Mark Karr didn't kill JonBenet Ramsey, he won't be the first to confess voluntarily to a crime he didn't commit. The motivation for these phony admissions, says criminologist Jim Fisher, author of Fall Guys: False Confessions and the Politics of Murder, can be "mental illness or extreme guilt over another crime, or they're just yearning for the attention a big case brings, the chance to be in the history books."

That quest for notoriety has fueled legions of false confessions to high-profile crimes. After Charles Lindbergh's infant was kidnapped and murdered in 1932, more than...